1. Field of the Invention
This invention is directed toward improvements in drawing systems. The invention is more particularly directed toward improvements in drawing systems of the type employing drawing or drafting boards.
2. Description of the Prior Art
Drawing or drafting boards are employed to provide a large, flat, rectangular working surface when drawing or drafting. A sheet of drawing paper is attached by tape or other suitable fastening means to the working surface of the board. If the drawing on the paper is not completed during a working session, the paper is usually removed from the working surface of the board and stored to protect the drawing. When further work is to be done on the drawing, it must be squared and remounted on the working surface.
U.S. Pat. No. 3,180,028, Roccati, 1965, illustrates a continuous conveyor type belt mounted on large rollers and sliding on a drawing board. One of the rollers is coupled to a parallel shaft and to a drive sleeve. The conveying surface is connected at its lateral edges by means of a perforated rubber strip. The size of the rollers also reduces the draftsman's accessibility to the drawing board. The connection, as shown in the Roccati patent, has very little elastic play and cannot be easily removed or cannot be easily re-aligned in order to place the conveying band properly on the drawing table. It has been found that if small diameter rollers are used at each end of the board, the unsupported span over which such rollers extend will cause deflection in most rollers, thereby causing the distance between the axes of the rollers at the center of the board to be less than the distance between the axes of the rollers near the supported ends of the rollers. Further, varying temperatures may affect different areas of the conveyor band at different time periods.